Method of dyeing collagen staple fiber

ABSTRACT

A method of dyeing collagen fiber includes providing collagen fiber and dyeing the collagen fiber.

FIELD OF THE INVENTION

This invention relates to dyeing processes of manufactured collagen staple fiber, collagen-based yarn and collagen-based fabric.

BACKGROUND OF THE INVENTION

There is an increasing interest to develop environmentally sustainable materials that exhibits properties that makes them replaceable or supplemental as material for diverse purposes. Leather is a widely used material in a vast of applications, such as furniture, clothes, shoes, handback and accessories and in the automobile industry. To meet the request of many different applications or consumers wishes for different appearances, treatments such as dyeing is an important of the manufacturing process of leather. A challenge is however that leather exhibits inferior properties e.g. in relation to variations, level of penetration and inhomogeneity and wasteful amounts of dye and chemicals.

SUMMARY OF THE INVENTION

The invention relates to a method of dyeing collagen fiber comprising the steps of

-   -   providing collagen fiber and     -   dyeing the collagen fiber.

In an embodiment of the invention, the collagen fiber (CF) is in the form of a collagen-based filament.

In an embodiment of the invention, the collagen fiber (CF) is processed into a staple fiber (SF).

In an embodiment of the invention, the collagen fibers are reconstructed fiber staple fibers produced on the basis of a number of mechanically sub-divided or grinded protein fibrils.

In an embodiment of the invention, the step of dyeing the collagen fiber is performed prior to the processing of the fiber into a staple fiber (SF).

According to an advantageous embodiment of the invention, the step of dyeing is performed on collagen fiber in the form of filament thereby making it possible to provide a reproducible dyeing of the collagen fiber on a manufacturing scale, where it is possible to adjust the collagen fiber to the desired color. In this connection, it should be noted that the intended use for the dyed collagen fiber is for fabrics, e.g. wearables or shoes, and that intended color has to be obtained quite precisely when compared to other applications, such as artificial hair etc. Nuances in color is very easily detected by the human eyes in fabrics, and such nuances may at certain levels be desired, but at others, such nuances should be avoided. In this context, it should be noted that the content of collagen in the collagen fiber makes the dyeing process different from e.g. conventional dyeing of e.g. synthetic or partly synthetic textiles.

In an embodiment of the invention, the collagen fiber is re-tanned in the form of staple fiber or filament prior to dyeing.

The re-tanning may thus be performed on the collagen-based filament or the collagen-based staple fiber.

The use of the term re-tanning is inferring, that the collagen fiber has been subject to some kind of chemical stabilization of the collagen proteins, i.e. a tanning.

In an embodiment of the invention, the collagen fiber is subject to a process step of de-acidification prior to re-tanning or as a part of the re-tanning

In an embodiment of the invention, the collagen fiber is subject to a process step of de-acidification subsequent to the acidification step after re-tanning or as a part of the re-tanning and wherein the collagen fiber has been subject to at least on tanning agent between the acidification step and the basification step.

Again, in the present context, the terminology collagen fiber encompasses both a filament or a staple fiber.

In an embodiment of the invention, the collagen fiber comprises tanning agent prior to re-tanning.

It is preferred that the collagen fiber, as staple fiber or in the form as filament, comprises tanning agent prior to the tanning to be performed prior to dyeing. It is therefore logically the regarded as a re-tanning. The step may nevertheless be referred to as a tanning step and still be in the context of a re-tanning, as tanning in the present context is regarded as the overall process of stabilizing the collagen of the applied fibers. It may therefore occur in the text of the present application that a re-tanning is referred to as a tanning without compromising the above definitions, whereas the wording re-tanning will always refer to a tanning of collagen fiber which has previously been subject to some degree of tanning of the collagen proteins comprised in the fiber.

In an embodiment of the invention, the content of tanning agent in the collagen fiber is increased during re-tanning of the collagen fiber with at least 10% by weight of the tanning agent contained in the collagen fiber previous to re-tanning.

In an embodiment of the invention, the collagen staple fiber is spun into a yarn (Y) subsequent to dyeing.

In an embodiment of the invention, the yarn is subsequently processed into a fabric.

In an embodiment of the invention, the collagen staple fiber is spun into a yarn (Y) and wherein the color of the yarn (Y) is subsequently modified into a neutral base color.

In an embodiment of the invention, the yarn is modified into a neutral base color and then reeled into a plurality of reels having the neutral base color.

In an embodiment of the invention, the yarn in a neutral base color is processed into a fabric prior to dyeing.

In the present context, it is understood that the invention makes it possible to perform the dyeing of the yarn into the final desired use-color on a yarn having a base color which is able to be dyed without a complex adaptation of the dyeing process in dependency of the desired end-color of the yarn or fabric.

A reel in the present context may be regarded as an object on which a yarn is wound, but it may also be broadly regarded as a yarn structure with no central object.

In an embodiment of the invention, the yarn having the neutral base color is reeled into a plurality of yarn reels.

In an embodiment of the invention, the yarn in a neutral base color is rolled up on a plurality of reels prior to dyeing and subsequently a subset from the plurality of spools is selected for dyeing the yarn in one color and another subset from the plurality of spools is selected for dyeing the yarn in another color.

Providing the yarn with the same neutral base color has the advantages of reproducible dyeing processes, wherein the final products obtain the same color without having to include several adjustments in the dyeing process. Further, the non-dyed yarn serves as flexible stock items that can be dyed on order.

In an embodiment of the invention, the percentage by weight of the collagen in the collagen fiber is at least 20 percent by weight of the collagen fiber, such as at least 30 percent by weight of the collagen fiber, such as least 40 percent by weight of the collagen fiber.

It is noted that the provided fiber may constitute a mixed-feature fiber, where the collagen fiber as such may comprise amounts of other materials, such as cellulose, keratin, other polysaccharides, proteins or molecules desirable for a desired final property of the fiber. The final desired property may e.g. be determined on the basis strength, elasticity, softness, antibacterial properties, etc. The desired properties may of course depend on the final application. The weight is referenced to collagen fiber in the form of filament or staple fibers.

In an embodiment of the invention, the percentage by weight of the collagen in the collagen fiber is at least 70 percent by weight of the collagen fiber, such as at least 80 percent by weight of the collagen fiber, such as at least 90 percent by weight of the collagen fiber, such as at least 99 percent by weight of the collagen fiber.

It is noted that a high content of collagen in the fiber will facilitate a subsequent manufacturing of yarn and a fabric of leather yarn having leather properties if the content of collagen protein in the yarn is high and/or as close as possible to 100%/the obtainable max value.

In an embodiment of the invention, the dyeing is performed at a pH within 5 to 11, preferably within a pH of 6-8.

In an embodiment of the invention, the dyeing is performed at a pH within 3-8, preferably within 5-6.

In an embodiment of the invention, dyeing is performed without pH adjustment.

In an embodiment of the invention, the dyeing is performed after a basification step performed on the collagen fiber.

According to an advantageous embodiment of the invention, the dyeing is performed at a time where the pH is relatively close to neutral. This has many benefits in the present context. One of such benefits is that the dyeing can be performed at a relatively safe environment and thereby offering the option of re-dyeing until a desired color has to be obtained. In the present context it should be noted that collagen, contrary to other substances to be dyed may be somewhat tricky in terms of obtaining a desired end-color.

A basification, which may thus also be regarded as a neutralization, is thus a very attractive pretreatment insofar, an earlier part of the process is performed at pH values below e.g. 4.

In an embodiment of the invention, a collagen-based staple fiber is spun into a yarn (Y) by spinning of a plurality of collagen staple fibers (SF) into a yarn (Y), wherein the yarn (Y) comprises a spun bundle of collagen staple fibers (SF), and wherein the manufactured yarn (Y) is subsequently subject to dyeing (D).

The spun yarn will typically be spun into continuous lengths of spun staple fibers and the length of the yarn may typically be much longer than the length of the individual staple fibers. In order to facilitate spinning, the collagen staple fibers may e.g. be provided in a kind of wool of staple fibers and the wool may then be carded and spun into the yarn subsequently. The carding process disentangles and intermixes fibers to produce a continuous web or sliver suitable for subsequent processing such as spinning.

By rolling up the yarn in this context may in this context mean any suitable ways of rolling up the yarn for an easier handling. Rolling up may be on spools or the similar.

Generally, it is noted that the length of the yarn (Y) has a length which is substantially greater than the length of the collagen staple fibers (SF).

It should be noted that the meaning of dyeing the collagen staple fiber (SF) after the staple fibers have been spun into a yarn simply is that the collagen staple fibers (SF) of the yarn will be dyed when the yarn is dyed. The access of the dye may of course be somewhat easier when dyeing the staple fibers prior to spinning, but the final color of the dyed yarn may be easier to control when dyeing the yarn. It is also noted that the dyeing of yarn formed of collagen staple fibers instead of collagen staple fibers prior to spinning also has the advantage that the final color may be established as late as possible in the manufacturing process. This is in particular an advantage when the collagen comprised in the collagen staple fibers has been chemically stabilized earlier. Such a chemical stabilization may by itself very often invoke a color modification which has to be dealt with when establishing the final color of the yarn.

It should be noted that the desire of obtaining a yarn and/or fabric based on spun collagen fibers is to obtain a fabric having or being dominated by attractive properties normally being associated with leather. In the present context, it is possible to obtain a fabric, where effective dyeing of the fabric, whether being performed on the filament, staple fiber, the yarn or the final fabric, may be performed fast and more predictive than conventional dyeing of leather.

It is also noted that a surprising effect of dyeing of collagen-based fiber subsequent to formation of the fiber as that such dyeing is in fact comparable with the intended property of the final dyed fabric in spite of the fact that such a final dyeing would infer that the required or desired tanning should likely be performed prior to such finalization of color.

In an embodiment of the invention, the dyeing (D) of the collagen yarn (Y) is performed subsequently to the spinning of staple fibers into a yarn (Y) and prior to a further step of processing the yarn into a fabric.

In an embodiment of the invention, the collagen yarn is subject to re-tanning prior to dyeing.

The re-tanning may thus be performed on the collagen-based filament or the collagen-based staple fiber.

The use of the term re-tanning is inferring, that the collagen fiber has been subject to some kind of chemical stabilization of the collagen proteins, i.e. a tanning.

In an embodiment of the invention, the yarn is subject to a process step of acidification prior to re-tanning or as a part of the re-tanning.

In an embodiment of the invention, the yarn is subject to a process step of basification subsequent to the acidification step after re-tanning or as a part of the re-tanning and wherein the yarn has been subject to at least one tanning agent between the acidification step and the basification step.

Again, in the present context, the terminology collagen fiber encompasses both a filament or a staple fiber.

In an embodiment of the invention, the collagen fiber of the yarn comprises tanning agent prior to re-tanning.

It is preferred that the collagen fiber, as staple fiber or in the form as filament in the yarn, comprises tanning agent prior to the tanning to be performed prior to dyeing. It is therefore logically the regarded as a re-tanning in such a situation. The step may nevertheless be referred to as a tanning step and still be in the context of a re-tanning, as tanning in the present context is regarded as the overall process of stabilizing the collagen of the applied collagen proteins of the fibers It may therefore occur in the text of the present application that a re-tanning is referred to as a tanning without compromising the above definitions, whereas the wording re-tanning of fabric will always refer to a tanning of collagen fiber of a fabric which has previously been subject to some degree of tanning of the collagen proteins comprised in the fabric.

In an embodiment of the invention, the content of tanning agent in the collagen fiber is increased during re-tanning of the yarn with at least 10% by weight of the tanning agent contained in the yarn previous to re-tanning.

The pH may be acidic when the chromium is introduced to ensure that the chromium complexes are small enough to fit in between the fibers and residues of the collagen.

Once the desired level of penetration of chrome into the substance is achieved, the pH of the material is raised again to facilitate the process (basification).

The pH may be e.g. lowered (e.g. to pH 2.8-3.2) to allow penetration of the tanning agent and following penetration the pH may be raised to fix the tanning agent (e.g. pH 3.8-4.2 for chrome or higher)

A further advantage of the invention is that the pH adjusting step is faster than when pH adjusting in the conventional tanning process of leather because the fabric will respond to the acid due to the more accessible conformation of the yarn/fabric.

In an embodiment of the invention, the content of tanning agent in the collagen fiber is increased during re-tanning of the yarn with at least 10% by weight of the tanning agent contained in the yarn previous to re-tanning and where the collagen fiber of the final yarn contains at least 1% by weight of tanning agent which has been provided to the fiber prior to the re-tanning.

In an embodiment of the invention, the yarn is processed into a fabric subsequent to dyeing of the yarn.

In an embodiment of the invention, the percentage by weight of the collagen in the collagen yarn is at least 20, such as at least 30, such as least 40 percent by weight of the collagen yarn.

It is noted that the provided yarn may constitute a mixed-feature yarn, where the yarn may comprise amounts of other materials, such as cellulose, wool, etc., desirable for a desired final property of the yarn. The final desired property may e.g. be determined on the basis strength, elasticity, softness, antibacterial properties, etc. The desired properties may of course depend on the final application.

In an embodiment of the invention, the percentage by weight of the collagen in the collagen yarn is at least 70, such as at least 80, such as at least 90 percent by weight of the collagen yarn.

It is noted that a high content of collagen in the yarn will facilitate a subsequent manufacturing of a fabric of leather yarn having leather properties if the content of collagen protein in the yarn is high and/or as close as possible to 100%/the obtainable max value.

In an embodiment of the invention, the dyeing is performed at a pH range within 5 to 11, preferably within a pH range of 6-8.

In an embodiment of the invention, the dyeing is performed after a basification step performed on the collagen fiber.

In an embodiment of the invention, the collagen fabric is provided on the basis of collagen yarn,

wherein the yarn is spun on the basis of a plurality of collagen staple fibers, and

wherein the provided fabric is subject to dyeing.

In an embodiment of the invention, the provided fabric is re-tanned prior to dyeing.

The re-tanning may thus be performed on the collagen-based filament or the collagen-based staple fiber.

The use of the term re-tanning is inferring, that the collagen fiber of the fabric is being subject to some kind of chemical stabilization of the collagen proteins, i.e. a tanning, prior to dyeing but subsequent to the providing of the collagen based fabric.

In an embodiment of the invention, the fabric is subject to a process step of acidification prior to re-tanning or as a part of the re-tanning

In an embodiment of the invention, the fabric is subject to a process step of basification subsequent to the acidification step after re-tanning or as a part of the re-tanning and wherein the fabric has been subject to at least one tanning agent between the acidification step and the basification step.

In an embodiment of the invention, the fabric comprises tanning agent prior to re-tanning.

It is preferred that the collagen fiber used in the fabric comprises tanning agent prior to the tanning to be performed prior to dyeing. The subsequent tanning is therefore logically regarded as a re-tanning. The step may nevertheless be referred to as a tanning step and still be in the context of a re-tanning, as tanning in the present context is regarded as the overall process of stabilizing the collagen of the applied fibers. This will also be covered by the so-called re-tanning step, but persons skilled in the art would very often consider the step of re-tanning more focused on softening of the collagen fiber than chemical stabilization. It may therefore occur in the text of the present application that a re-tanning is referred to as a tanning without compromising the above definitions, whereas the wording re-tanning will always refer to a tanning of collagen fiber which has previously been subject to some degree of tanning of the collagen proteins comprised in the fiber.

In an embodiment of the invention, the content of tanning agent in the fabric is increased during re-tanning of the fabric with at least 10% by weight of the collagen fiber.

In an embodiment of the invention, the percentage by weight of the collagen in the fabric is at least 20 percent by weight of the collagen, such as at least 30 percent by weight of the collagen, such as least 40 percent by weight of the collagen in the fabric.

It is noted that the provided fabric may constitute a mixed-feature fabric, where the fabric may comprise amounts of other materials, such as cellulose, keratin, other proteins or molecules desirable for a desired final property of the fabric. The final desired property may e.g. be determined on the basis strength, elasticity, softness, antibacterial properties, etc. The desired properties may of course depend on the final application. The weight is referenced to collagen fiber in the form of filament or staple fibers.

In an embodiment of the invention, the percentage of collagen in the fabric is at least 70 percent by weight of the collagen, such as at least 80 percent by weight of the collagen, such as at least 90 percent by weight of the fabric, such as at least 99 percent of the collagen in the fabric.

It is noted that a high content of collagen in the fabric will facilitate a fabric of leather yarn having leather properties if the content of collagen protein in the yarn is high and/or as close as possible to 100%/the obtainable max value.

In an embodiment of the invention, the fineness of the fibers of the yarn is less than 10 dTex.

In an embodiment of the invention, the fineness of the yarn is within a range of about 10 Tex to 300 Tex.

The inventors of the present invention have discovered that by dyeing manufactured collagen fabric several advantages can be obtained, such as less use of dye and chemicals, faster processes, higher color stability and higher reproducibility.

Important advantages of using collagen-based fabric is the uniformness of the material that results in effective penetration of the dye. The fabric can uniformly be in the same anionic state and pH adjustment will uniformly affect the whole fabric toward higher penetration and/or binding of the dye to the collagen-based fabric.

The higher penetration and/or binding of dye to the uniform collagen-based fabric may also have further advantages. The required amount of dye and chemicals may be significantly less than when dyeing conventional leather and therefore provide valuable benefits both for the environment, the workers producing the fabric, and the consumer of the products made from dyed collagen-based fabric.

Woven or weaved in this context defines processes such as knitting, weaving, crocheting, felting, braiding, plaiting or other methods of textile production known in the art and a fabric is within the invention understood as a cloth or other material made by any of these methods. The fabric may be similar and used where applicable for textiles and may exhibit properties with diverse strength, flexibility and/or stretch. The fabric may also display a dissimilar property throughout one piece of fabric. By selecting and tuning the content of fibers and processing steps, the fabric can be modified in softness, flexibility, surface texture, elasticity, thickness or other functionalities. Weaving is within the invention understood as a method of textile production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric. Knitting is within the invention understood as a method of textile production by looping a continuous yarn.

In an embodiment of the invention, the collagen fiber and/or collagen yarn and/or collagen fabric in the dyeing step is dyed with any dye relevant for dyeing leather and textile and at least one type of dye selected from the group of acid dyes, basic dyes, direct dyes, reactive dyes, chrome dye, milling dye, premetallized dyes, mordant dyes and sulfur dyes.

Examples of premetallized dyes may be NeolanYellow GR 175% (dye having color index (C.I) 99 of Ciba Specialty Chemicals), Neolan Bordeaux RM 200% (dye having C.I 194 of Ciba Specialty Chemicals, Neolan Blue 2G 250% (dye having C.I. 158 of Ciba Specialty Chemicals, IrgalanYellow GRL 200% (dye having C.I 116 of Ciba Specialty Chemicals), Irgalan Bordeaux EL 200% (dye having C.I 251 of Ciba Specialty Chemicals).

Examples of reactive dyes may be Levafix Brilliant Blue E-BRAN (dye having C.I 114 of Dystar Japan Ltd.), Levafix Brill. Red E-RN gran (Dystar Japan Ltd.), Levafix Golden Yellow E-G (dye having C.I27 of Dystar Japan Ltd.), Eriofast RedB (Ciba Specialty Chemicals), Cibacron Red P-BN GRAN (Ciba Specialty Chemicals), Lanasol Red 6G (dye having C.I 84 of Ciba Specialty Chemicals).

An example of Chrome dye may be Dimond BlackT01 (Dystar Japan Ltd.).

Examples of milling dues may be Polar Blue RLS 200% (Ciba Specialty Chemicals), Polar Red B 125% (dye having C.I. 249 of Ciba Specialty Chemicals), Polar Yellow 4G 160% (Ciba Specialty Chemicals), Suminol Milling Brilliant Red 3BN (Ciba Specialty Chemicals).

Examples of acid dyes may be Telon Red FRL Micro (Dystar Japan Ltd.), Telon Red M-BL 168% FRL (Dystar Japan Ltd.), Supranol Yellow 4GL (Dystar Japan Ltd.).

Examples of Direct dyes may be SiriusBlack VSFH/C (Dystar Japan Ltd.)

In an embodiment of the invention, the collagen fiber and/or collagen yarn and/or collagen fabric is dyed in the dyeing step with at least one kind of dye selected from the group of azo dyes, triarylmethane, hetero polycyclic, and anthraquinone.

Dyeing in this context is adding color to the fiber, yarn or fabric. Applying dye in solution or pigment, to confer dense, opaque color, may be performed in the drum or coloring agents may be sprayed or spread by hand (padding) onto the surface of the fabric.

Any suitable dye may be used, particular dyes that are appropriate for leather or other collagen materials. Dyes may include acid dyes, basic dyes, direct dyes, reactive dyes, premetallized dyes, mordant dyes and sulfur dyes.

The size and shape of the dye molecule may vary; small compact molecules are mobile and form salt-linkages and are represented by traditional penetrating acid dyes (anionic) and basic dyes (cationic). Lange, long or planar dye molecules are represented by direct dyes (anionic, neutral exhausting and surface dyeing).

The dyes may include molecules containing a chromophore group, including azo dyes, triarylmethane, heteropolycyclic, and anthraquinone.

In an embodiment of the invention, the dyeing step includes the use of color-fixing agents.

Color-fixing agents may be used to improve the dye-fastness and agents such as quaternary ammoniums may be applied. Membranes may also be formed to cover dyes om fabric surfaces. Color-fixing agents may increase rubbing resistance.

In an embodiment of the invention, the method comprises fat-liquoring.

Fatliquoring may be applied to the method and may prevent that the fiber structure resticks during drying and further the process may provide an increased elasticity, increased tear strength and soften the material, e.g. the collagen fiber, collagen yarn and/or the collagen fabric.

The fatliquoring process may be made simultaneously to dyeing but may also as an independent process. Vegetable, animal or synthetic oils, fats and waxes may be used.

Fatliquoring may advantageously be applied to the yarn before dyeing the yarn.

Finishes may also be applied to the method on fibers, collagen yarn and/or collagen fabric. These may include wax surface finishes to improve water resistance, hardening the surface and protect the color. Finishes may include solvents, binders, plasticizers, pigments and specialized waxes.

Further, relevant finishing agents and/or processes suitable for handling yarn textiles may be applied to the method.

When dyeing of protein textiles such as wool conventionally, the initial fixation of molecules by salt-linkages may be re-arranged by promoting migration of the dyes within and throughout the textile at high temperatures (boil). This strategy may not be possible when working with leather because of low shrinkage temperatures and possible loss of fiber strength. To overcome this challenge, tannery dyers have adopted strategies to ensure that the dyeing process is slow and gradual. However, in the present context it is possible to provide a faster and more effective dyeing process of fibers containing collagen or yarn/fabrics made on the basis of fibers containing collagen

An advantage of the uniform collagen-based material may be that the processes related to dyeing the fabric are faster than when dyeing conventional leather caused by more efficient penetration which may be highly economically valuable but also beneficial for the workers exposure time for dye and chemicals.

pH adjusting may be made by the use of formic acid, acetic acid, sulfuric acid, sodium hydroxide, or sodium carbonate.

Challenges when dyeing leather may be the 3-dimensional structure that makes a uniform treatment difficult, particular in penetration of dye. Penetration can be helped if the material is uniformly anionic and otherwise if there is a cationic zone, it will be an effective barrier to further penetration.

In an advantageous embodiment of the invention, fat liquoring is performed to the yarn prior to dyeing, thereby providing a “stand-alone” non-dyed leather yarn.

In an embodiment of the invention, the method comprises temperatures between 20-100 degrees Celsius. Preferably between 27-60 degrees Celsius.

In embodiments of the invention, it is preferred to dye the fabric whilst conferring a re-tanning effect.

The use of reactive dye could constitute a form of re-tanning, because they bond to basic side chains with one or two covalent links.

In an embodiment of the invention, the method comprises at least one additional step including i.e. impregnation, oiling, drying and/or softening.

In an embodiment of the invention, the collagen fiber (CF) is reconstructed fibers based on natural collagen.

In an embodiment of the invention, the collagen fiber (CF) is a reconstructed fiber based on natural collagen and where the reconstructed fiber comprises at least 40% by weight of natural collagen.

In an embodiment of the invention, the collagen yarn comprises at least 40% by weight of collagen protein.

In an embodiment of the invention, the collagen yarn further comprises non-collagen protein.

In an embodiment of the invention, the collagen yarn further comprises 1 to 60% by weight of non-collagen protein.

In an embodiment of the invention, the collagen yarn further comprises 1 to 60% by weight of natural and/or synthetic textile fiber.

In an embodiment of the invention, use of the yarn manufactured according to the method described in any of the preceding claims, wherein the yarn is incorporated into an item.

In an embodiment of the invention, use of the collagen fabric comprising the manufactured yarn described in any of the preceding claims, wherein the fabric will be used for an item.

In an embodiment of the invention, leather yarn according to the invention, and wherein the collagen fiber is made according to the invention.

In the present context, leather yarn is understood as a yarn at least based on collagen proteins and/or collagen protein fibrils.

In an embodiment of the invention, the color of yarn is provided in a neutral base color.

In an embodiment of the invention, the yarn in the neutral base color is reeled up on a plurality of reels.

In an embodiment of the invention, the yarn having the neutral base color is rolled up on a plurality of reels prior to dyeing.

In an embodiment of the invention, the yarn in a neutral base color is rolled up on a plurality of reels prior to dyeing and subsequently a subset from the plurality of spools is selected for dyeing the yarn in one color and another subset from the plurality of spools is selected for dyeing the yarn in another color.

Providing the yarn with the same neutral base color has the advantages of reproducible dyeing processes, wherein the final products obtain the same color without having to include several adjustments in the dyeing process. Further, the non-dyed yarn serves as flexible stock items that can be dyed on order.

In an embodiment of the invention, the collagen fibers have a tenacity of more than 3 g/denier, such as at least 5 g/denier, such as at least 7 g/denier. In an embodiment of the invention, leather yarn according to any of the preceding claims, wherein the yarn comprises tanning agents in at least 1% by weight of the yarn and dye in at least 0.1% by weight of yarn.

In an embodiment of the invention, leather yarn according to any of the preceding claims, wherein the yarn comprises tanning agents in an amount of 1 to 10% by weight of the yarn and dye in an amount of 0.1 to 10% by weight of the yarn in at least 0.1% by weight of yarn.

In an embodiment of the invention, leather fabric, the leather fabric being produced on the basis of leather yarn according to the invention and wherein the collagen fiber is made according to the invention.

In an embodiment of the invention, leather fabric according to the invention, wherein the collagen fibers have a tenacity of more than 3 g/denier, such as at least 5 g/denier, such as at least 7 g/denier.

In an embodiment of the invention, leather fabric according to claim 48, wherein the fabric comprises tanning agents in at least 1% by weight of the fabric and dye in at least 1% by weight of fabric.

In an embodiment of the invention, leather shoe (S) comprising a sole (SO) and an upper part (UP),

wherein the upper part (UP) is at least partly comprised of leather fabric,

wherein the leather fabric is produced on the basis of leather yarn,

wherein the fabric of the shoe comprises tanning agents in at least 1% by weight of the fabric and dye in at least 1% by weight of fabric.

In an embodiment of the invention, leather shoe according to the invention, wherein the leather fabric and/or the leather yarn is produced according to the invention.

In an embodiment of the invention, leather shoe according to the invention, wherein the leather fabric is applied in the upper part of the shoe.

In an embodiment of the invention, leather shoe according to the invention, wherein the leather fabric is applied as a shoe lining (SL) or as a part of a shoe lining.

The shoe lining is the material inside the shoe that in some applications comes in contact with the entire foot: the sides, top and heels, or at least some of these parts of the foot. A purpose of the lining is to cover the inside seams of the shoe and lengthen the shoe's lifespan. Linings made according to the present invention may cushion and comfort the foot or draw out moisture.

Thus, the leather fabric lining feels soft on the skin and will conform to the shape of the foot over time. It's also durable and allows air flow, letting moisture evaporate. Although leather is the highest quality material for lining, certain shoes, particularly athletic shoes, don't use leather lining because the leather adds extra weight. The present invention facilitates such use as the leather fabric may provide all or many of the advantages of conventional leather but also be present in a light weight, thereby increasing to application to e.g. athletic shoes, but also by realizing that the incorporated dye may be matched very well to fabric e.g. in terms of amount contrary to conventional leather where such a process is extremely time consuming and difficult to control in terms of desired end-color.

Overall it is noted that the leather fabric provided according to the present in invention is very breathable and that a shoe provided according to the present invention may not only be relatively color-durable but also be used both as out and optional inner layer of a shoe thereby providing a shoe having an upper part which very breathable compared to conventional shoe fabric.

The invention moreover relates to a fat-liquored leather yarn, wherein the leather yarn is tanned and non-dyed.

In an embodiment of the invention, the fat-liquored leather yarn is manufactured according the invention.

The invention moreover relates to a leather fabric manufactured of leather yarn according to the above method.

In an embodiment of the invention, the leather fabric is manufactured of leather yarn, wherein the leather yarn is provided on basis of a solution.

In an embodiment of the invention, the leather fabric is manufactured of leather yarn, wherein the leather yarn is provided on basis of a suspension.

In an embodiment of the invention, a plurality of yarn reels SP, wherein the yarn is at least based on collagen protein and wherein the yarn reels are provided in a neutral base color.

In an embodiment of the invention, a plurality of yarn reels, wherein the yarn is at least based on collagen protein and wherein the yarn reels are provided in a neutral base color facilitating subsequent dying into different colors with different dye color, but with a due process which is substantially the same.

In an embodiment of the invention, a plurality of yarn reels, wherein the yarn is at least based on collagen protein and wherein the yarn reels are provided in a neutral base color and wherein the yarn of the reels is provided according to the method according to the invention.

THE FIGURES

The invention will be described in the following with reference to the drawings where,

FIGS. 1A, 1B and 1C illustrate an example of dyeing collagen fibers (CF) before manufactured into a yarn (Y), dyeing collagen-based yarn (Y) before manufactured into a fabric (F) and dyeing a fabric (F).

FIGS. 2A, 2B, 2C and 2D illustrate the dyeing processes according to embodiments of the invention,

FIG. 3 illustrates a shoe according to an embodiment of the invention and

FIG. 4 illustrates an example of pre-dyeing (PD), spooling (SP) and dyeing (D) collagen-based yarn (Y)

DETAILED DESCRIPTION

In the description and claims, the percentage values relating to an amount of material are percentages by weight (wt. %) based on the total weight of the filament or the staple fiber in question unless otherwise indicated. The word “comprising” may be used as an open term, but it also includes the closed term “consisting of”.

As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

As used herein, “at least one” is intended to mean one or more, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

The term “collagen” refers to any one of the known collagen types of the at least 28 distinct collagen types, each serving different functions in animals. The major component of skin is type I collagen although other types of collagen may also be used to form leather. Collagens are proteins, i.e. they are made up of amino acids. They can be separated into alpha-amino acids and beta-amino acids. Each one features a terminal amino group and a terminal carboxyl group, which become involved in the peptide link and a sidechain attached to the methylene group in the center of the molecule. When the amino acids are linked together to form proteins, they create an axis or ‘backbone’ to the polymer, from which the sidechains extend. It is the content and distribution of the sidechains that determine most of the properties of any protein.

The term “collagen fibrils” refers to nanofibers composed of triple helices of collagen molecules (tropocollagen). The fibrils may have diameters ranging from 10-100 nanometers and are usually not found alone but rather a part of greater hierarchical structures. Each fibril may be interlocked with its neighboring fibrils to form a collagen fiber. Collagen fibrils may originate from shavings, leather pulp and/or tanned hides including the waste material from tanning process. The collagen fibrils may originate from different but typically skin.

The term “collagen fiber” refers to tightly packed collagen fibrils that exhibit a high degree of alignment in the direction of the fiber and is often longer than it is wide. Variations of organization or crosslinking of fibrils and fibers may provide strength to the material. Collagen fiber may comprise staple fibers or filaments. The fiber may be a reconstructed fiber and may comprise other material than collagen.

The term “collagen filament” and “collagen filament” may be used interchangeable in present context.

The term “staple fiber” refers to fibers of discrete length and may be of any composition. The staple fibers may be further processes to provide an item, such as a yarn or non-woven material.

The term “wool” refers to a fluffy material of staple fibers or fibers or reconstructed natural based fiber. The term wool may also be used as natural fiber based wool or staple fiber wool.

The term “reconstructed” fiber refers to staple fibers produced on the basis of a number of mechanically sub-divided protein fibrils. The reconstructed fiber may be formed from a protein suspension directed through a nozzle onto a surface for drying. The suspension is dried to remove water and solvent from the suspension and thereby the reconstrued fiber is formed on e.g. a belt or a cylinder surface. Such a manufacturing method of reconstructing fibers on the basis of protein fibrils is e.g. illustrated in WO 2018/149950 or WO 2018/149949 for the use in connection with collagen.

Other starting materials may of course be added to the collagen, there facilitating reconstructed fibers based on a mixture of fibrils derived from collagen material such as leather and fibrils derived from e.g. cellulose sources.

The term “manufacturing process” as used herein, may be the process where fibers forms an inhomogeneous network of natural fiber based raw wool and processes through a mechanical carding process that disentangles and intermixes fibers to produce a continuous web or sliver suitable for subsequent processing such as spinning.

The term “sliver” as used herein, is a long bundle of fiber that is generally used to spin yarn and created by carding or combining the fibers, which is then drawn into long strips where the fibers are parallel. A sliver may be slightly twisted and considered as a loose and soft robe-like textile fiber.

Spinning is the twisting together of drawn-out strands of fibers to form yarn and can processed with ring spinning or other systems could include air-jet and open-end spinning.

Yarn is a long continuous length of interlocked fibers suitable for use in the production of fabric. Yarn may be spun from a variety of materials, including variants of collagen

The yarn may be fabricated or manufactured into woven fabric and in this context, it defines processes such as knitting, weaving, crocheting, felting, braiding, plaiting or other methods of textile production known in the art and a fabric is within the invention understood as a cloth or other material made by any of these methods.

The term “tanning” is used as the conventional ways of treating leather and may be applied to the invention. The technical definition of tanning is well known in the art, but briefly, according to Anthony D. Covington “Tanning Chemistry” chapter 10, the only strict definition of tanning is the conversion of a putrescible organic material into a stable material capable of resisting biochemical attack. Tanning involves a number of steps and reactions depending on the initial material and the final product.

The term “post tanning” as used herein may include processes such as pressing, shaving, retanning, dyeing and fatliquoring, drying, staking, milling and sanding. Products used for the post-tanning processes may belong to the following categories: degreasing, retanning, tannins/tanning agents, fatliquors, neutralisers, colourants and resins.

The term “basification” as used herein may also in this context refer to de-acidification as the main point of the process is not necessarily to obtain a basic pH, but at least to raise the pH.

The term “dye” or the term “dyeing” is in the present context referring to dyeing substances other that chromium-based compounds as typically used within the art as tanning agents, although it is noted that e.g. chromium-based substances during conventional tanning typically results in a bluish coloring of the tanned leather. In the present context, dye or dyeing thus refer to substances added with the purpose of obtaining a desired color. In other words, such a dyeing within the scope of the invention would preferably be performed at a pH level relatively close to neutral, or at least above 4.

Referring to FIGS. 1A, 1B and 1C, a schematic view of a process according to an embodiment of the invention is shown.

Further embodiments are illustrated in FIG. 2, and FIG. 3 all of these embodiments may be understood in the light of FIGS. 1A-1C and the discussion thereof below.

Returning to FIGS. 1A and 1B illustrating some principles of advantageous embodiment of the invention, FIG. 1A illustrates the components throughout a process flow. Initially collagen fibers (CF) are spun into yarn (Y) and then subjected to a dyeing process.

Basically, it should be understood that the applied collagen fibers may consist of natural collagen fibers, e.g. provided according to the loosening method described in EP 1 736 577B or alternatively be manufactured as fibers according to e.g. WO 2018/149950, WO 2018/149949 or U.S. Pat. No. 3,556,969, or WO 2017/142896 or 2007/225631 A1. According to the latter, the collagen fiber should be loosened from the provided non-woven-structure.

The collagen fiber in the present context is generally understood as a fiber comprising collagen protein in an amount of at least 20% by weight of the fiber, such as at least 40% by weight of the fiber, such as at least 60% by weight of the fiber, such as at least 80% by weight of the fiber.

The collagen fiber in the present context has several benefits for use in the present invention, e.g. by providing stretch to a final fabric made according to the provisions of the invention.

Yarn is here understood as a kind of minimum structure of bundled collagen fibers extending in the direction of length. The extension of the bundled structure can in principle be infinite, although this is of course not a real-world application.

Yarn is further understood as any known type of yarn comprising single yarn, or one-ply; ply, plied, or folded; or as a cord, including cable and hawser types.

Single, or one-ply yarn is here understood as single strands composed of fibers or filaments that may be used as plural or alone. The yarn may be held together by at least a small amount of twist.

Ply, plied, or folded yarns are here understood as two or more single yarns twisted together.

Cord yarn is here understood as a yarn produced by twisting ply yarns together.

Fabric (F) is understood as a woven material and a fabric processed from yarn may possess the advantages of using different methods for processing such as weaving, knitting, crocheting, felting, braiding, plaiting, or other methods of textile production known in the art.

The fabric (F) within the scope of the invention may comprise different fibers and/or yarn such as, but not limited to, wool, cellulose, polyester, silver, elastic etc.

The inventive dyeing (D) step may be processed in a dye bath and may further e.g. be processed in rotating barrels. Dyeing in rotating barrels may also be understood as drum dyed. In this process the dye may also be fixed, and excess color may be rinsed out.

Generally, it should be noted that the dyeing process may be applied with any suitable dyeing equipment designed to dye according to the provisions of the invention.

FIG. 2A-2C discloses different ways of applying color within the scope of the invention wherein some embodiments are shown, and others may be applied.

FIG. 2A shows exemplary an embodiment of the invention.

With reference to the drawing, a collagen fiber CF is initially subjected to an acidification ACI as mentioned above. The collagen fiber CF is then subjected to a tanning process/re-tanning TP and subsequently subjected to a basification BAS. The collagen fiber is then subject to a dying step D resulting in a dyed collagen fiber which I then spun into a yarn by a yarn spinning process YSP. The dyed collagen based yarn may then subsequently be processed into a fabric F.

The present embodiment the illustrates that collagen fibers may be subjected to a tanning process TP, wherein the collagen fibers are first subjected to acidification and application of tanning agents. This could be a re-tanning and even a first tanning is possible. After application of tanning agents, the collagen fibers are subjected to basification and then to dye, wherein the details related to dyeing are described elsewhere in the description. The dyed fibers are subjected to yarn spinning and possibly manufacturing into fabric. Other processes may be applied in the process, such as i.e. fat-liquoring and optional further tanning is possible.

Different variants of the process will be described below. It is however noted that the principle difference in terms of process, not necessarily in terms of the obtained end-product, are referring to the same process steps, just organized in different logic sequences. Only the differences will be highlighted below.

FIG. 2B shows exemplary an embodiment of the invention collagen fibers subjected to a tanning process TP, wherein the collagen fibers CF are first subjected to yarn spinning YSP. After yarn spinning YSP the collagen fibers CF are subjected to acidification ACI, application of tanning agents TP, basification BAS and then dyeing D. The tanning process TP could be a re-tanning and even a first tanning. The dyed collagen fiber-based yarn may optionally be manufactured into fabric F and other processes may be applied such as i.e. fat-liquoring and optional further tanning is possible.

FIG. 2C shows exemplary an embodiment of the invention collagen fibers CF subjected to a tanning process TP, wherein the collagen fibers CF are first subjected to yarn spinning YSP and manufacturing into fabric F. The manufacturing of yarn into fabric is described in detail elsewhere in the description. The fabric is then subsequently subjected to acidification, application of tanning agents and basification and then dyeing.

FIG. 2D shows a further exemplary embodiment corresponding in terms of process steps to the already described process steps of FIG. 2A-C, but now where the collagen fiber CF is first spun into a collagen based yarn (Y) by a yarn spinning process (YSP) and where the produced yarn (Y) is subject to tanning agents and associated acidification and basification for promotion of the penetration of the tanning agents into the yarn. The yarn is then subsequently manufactured into a fabric F which is subsequently dyed in a dyeing step D.

The latter embodiment is generally considered a very advantageous embodiment of the invention as the semi-finalized yarn may be manufactured in a durable an distributable state, e.g. in a standard color which is relatively neutral or just a color being a natural result of the tanning agents applied. The standard colored dyed yarn, which is now considered a leather yarn, may then be dyed subsequently, e.g. after manufacturing of the fabric F. The basic point is that such process has never been attractive in relation to conventional leather not produced by leather yarn, as dyeing is a very complex and demanding step which should typically be performed at the tannery or at least at some kind to the manufacturer, e.g. a shoe manufacturer, requiring the leather in a certain color. This means at the very least that at lot of dyestuff are applied to hides or parts of hides and thereby restricting the use of the applied hide/leather.

The present invention basically facilitates in some embodiments that all yarn may of course be produced in a certain color or produced in one or few color appearances which may subsequently be subject to dyeing into the desired end-color. In other words. The dye is applied and fixed for the intended purpose at a very late stage of the process, thereby reducing risks of waste or the manufacturing for storage of leather materials which may be irrelevant at the time they are to be used.

FIG. 3 illustrates a further embodiment of the invention. The embodiment comprises a shoe (S) comprising a sole (SO) and an upper part (UP).

The upper part (UP) may be formed completely in fabric made according to the provisions of the invention. The upper part (UP), may also include a shoe lining (SL).

The shoe lining (SL) is the material inside the shoe that in some applications comes in contact with the entire foot: the sides, top and heels, or at least some of these part of the foot. A purpose of the lining is to cover the inside seams of the shoe and lengthen the shoe's lifespan. Shoe lining (SL) made according to the present invention may cushion and comfort the foot or draw out moisture.

Thus, the leather fabric lining feels soft on the skin and will conform to the shape of the foot over time. It's also durable and allows air flow, letting moisture evaporate. Although leather is the highest quality material for lining, certain shoes, particularly athletic shoes, don't use leather lining because the leather adds extra weight. The present invention facilitates such use as the leather fabric may provide all or many of the advantages of conventional leather but also be present in a light weight, thereby increasing to application to e.g. athletic shoes, but also by realizing that the incorporated dye may be matched very well to fabric e.g. in terms of amount contrary to conventional leather where such a process is extremely time consuming and difficult to control in terms of desired end-color.

Overall it is noted that the leather fabric provided according to the present in invention is very breathable and that a shoe provided according to the present invention may not only be relatively color-durable but also be used both as out and optional inner layer of a shoe thereby providing a shoe having an upper part which very breathable compared to conventional shoe fabric.

The upper part (UP) may be formed wholly or partly of single layered inventive leather fabric, it may be multilayered including a layer of inventive leather fabric and further optionally comprise a lining (SL).

The single layer of inventive leather fabric may e.g. form part of a vamp, quarter or a tongue of the upper part (UP).

The inventive leather fabric may be oriented towards the outside of the shoe and/or the inside.

If multilayered, the multilayer structure of the upper part may comprise one or more layers of the inventive leather fabric and at least one layer, e.g. a reinforcing layer, comprised of another material.

The multilayered fabric may be laminated together.

If laminated, the multilayered fabric of the upper part (UP) may comprise adhesive bonding a reinforcing fabric to the inventive leather fabric.

The reinforcing fabric may provide strength to the laminate, allowing the leather layer to be thin and the overall laminate to be flexible. The reinforcing fabric is therefore relatively thin and has high tensile strength, high tear strength and low elongation at break.

Suitably, the basis weight for the reinforcing fabric is below 150 g/m², typically below 100 g/m², more typically below 75 g/m², and most typically below 60 g/m².

A suitable method for measuring the basis weight of the reinforcing fabric is ASTM D3776.

Suitably, the ultimate tensile strength (breaking strength) of the reinforcing fabric is above 5 kN/m, more typically above 10 kN/m, or even above 15 kN/m.

The ultimate tensile strength expressed in kN/m is the pulling force required to break a 1 m wide sample of the material. A suitable test for measuring the ultimate tensile strength of the reinforcing fabric is ISO 3376: 2011. An alternative test specifically adapted for testing tensile properties of polymer matrix composites which could be used is ASTM D3039.

Suitably, the elongation at break of the reinforcing material (i.e. the elongation of the fabric when stretched to its breaking point) is less than 5%, typically less than 4%, or even less than 3%.

A suitable test for measuring the elongation at break is ISO3376:2011. An alternative test specifically adapted for testing the elongation properties of polymer matrix composites which could be used is ASTM D3039.

Suitably, the tear strength of the reinforcing material is above 25 N, typically above 50 N, or even above 75 N.

A suitable method for measuring the tear strength of the reinforcing material is ISO 3377-1:2011. An alternative test specifically adapted for testing the tear strength of polymer matrix composites which could be used is Mil-C-21189 10.2.4.

It will be clear from the above characteristics that the reinforcing fabric is very low basis weight (and hence typically very thin) yet typically has very high tensile strength and tear strength. Suitable materials that fulfil these requirements include fabrics which include at least one layer comprising high strength fibres.

By “high strength fibre” is meant a fibre having an ultimate tensile strength of above 1500 MPa. A suitable test for measuring the ultimate tensile strength of the fibre is ASTM D3822.

Typical high strength fibres include carbon fibres or high tensile strength polymeric fibres, with suitable high tensile strength polymeric fibres including polyethylene (particularly UHMWPE), polyaramid, polybenzoxazole, and polyaromatic esters.

Suitable high strength fibres that can be used in the reinforcing fabric therefore include carbon fibre, UHMWPE fibres such as Dyneema® available from DSM or Spectra® available from Honeywell; polyaramid fibres such as Kevlar® available from DuPont; polybenzoxazole fibres such as Zylon® available from Toyobo; and polyaromatic esters such as Vectran® available from Kuararay, Inc.

In this context, UHMWPE is “ultra-high molecular weight polyethylene”, which is sometimes also referred to as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE). UHMWPE is typically characterised by having an intrinsic velocity of at least 4 dl/g, desirably at least 8 dl/g. Generally, the intrinsic viscosity is less than 50 dl/g, typically less than 40 dl/g.

A suitable methodology for measuring intrinsic viscosity is ASTM D1601-2004 (at 135° C. in decalin, dissolution time 16 hours, with DBPC as an anti-oxidant in an amount of 2 g/l solution, by extrapolating the viscosity as measured at different concentrations to zero concentration).

The at least one layer in the reinforcing fabric comprising the high strength fibres may be woven or nonwoven. However, in order to benefit from the strength properties of the fibres, typically the at least one layer will contain the high strength fibres in an oriented fashion, such as woven (including uniweave), monodirectional or multidirectional fabrics.

Typically, the reinforcing fabric will comprise at least one layer having parallel high strength fibres. Said parallel high strength fibres may optionally be embedded in a resin matrix.

The multilayered fabric including the inventive leather fabric may e.g. form part of a vamp, quarter or a tongue of the upper part (UP).

The inventive leather fabric may be oriented towards the outside of the shoe and/or the inside.

The present invention basically facilitates in some embodiments that all yarn may of course be produced in a certain color or produced in one or few color appearances which may subsequently be subject to dyeing into the desired end-color. In other words. The applied dye is applied and fixed for the intended purpose at a very late stage of the process, thereby reducing risks of waste or the manufacturing for storage of leather materials which may be irrelevant at the time they are to be used.

FIG. 4 shows an example of an embodiment of the invention.

With reference to the drawing, a collagen-based yarn (Y) is going through a dye normalization step e.g. a pre-dyeing (PD) step and then wound on reels (SP) or similar suitable constructions for keeping yarn, and then dyed in a certain color e.g. red (RE), blue (BL) or yellow (YE).

The step of pre-dyeing or normalizing the color of the yarn is an optional step, however, a highly advantageous step wherein the color of the yarn achieves the same neutral base color and thereby optimizing the dyeing (D) process and promotes predictability in relation to the final dyeing process. This is a new a very interesting aspect of the invention as collagen-based products to be dyed, e.g. leather requires complex dyeing, and the results are typically obtained by trial and error, while the present embodiment of the invention makes it possible to perform a much more predictable dyeing, independent of the eventual color of the yarn.

Normalization of the color of the yarn in the present context is generally understood as a process to obtain yarn with the same neutral base color. That may be a discoloring, pre-dying, bleach or other relevant process to obtain a similar neutral base color. In other words, the pre-dyeing may not necessarily include the process of adding dye as bleaching or other chemical processing may be enough to provide the desired neutral base color.

According to an advantageous embodiment of the invention, a so-called neutral base-color may include a color which is able to be dyed into different relevant colors, such as black, white, yellow, red and blue, with basically the same dyeing process, just with colors of dye.

The collagen-based yarn may origin from several sources, e.g. hide such as e.g. bovine, other animals, leather waste or other sources of collagen and the basis color might be different depending upon the applied collagen source. Different treatments or processes of the hide, waste products etc. may change the color of the products and thereby also the initial color of the collagen-based yarn. Further, the hide may have been treated with tanning agents e.g. chrome tanning, that may provide a blue or grey color of the yarn. Hide treated with vegetable tanning agents may have a more white or yellow appearance. Applying the same amount of dye to yarns with different base colors may become irregular and aesthetic difficult to handle in the final products without applying extra dyeing, dependent on which color the final yarn is intended to have.

It should thus be noted that the present, although very advantageous, providing of a neutral base is extremely attractive both for the purpose of avoiding final leather/collagen-based yarn manufactured in an undesired color. Such a problem is often associated to conventional leather manufacturing. It, on the other hand, also makes it possible to re-user such waste products for the purpose of re-constructing collagen-based fibers, staple fibers, collagen-based yarn even if the waste product starting material has been dyed already or at least partially present in e.g. a bluish color due to an already performed chrome-tanning. In other words, the collagen material applied as the basis for the manufacture of staple fibers/filament/yam in the present invention, may due to different origin, be inherit very diverse

The term “spool” in this context means a physical object suitable for rolling up yarn for storage or further processes. It may also be a cone, reel or any other suitable object for rolling up yarn. The processing of rolling/winding up the yarn may also simply be performed as to provide a ball of yarn with no physical object onto which the yarn has be wound.

The collagen-based yarn may be tanned prior to or during the same process as dyeing. The tanning is optional and the collagen-based yarn may not need a tanning step if the collagen-based yarn has been manufactured from reconstructed fibers where the fibrils are already tanned.

FIGURE REFERENCES

-   ACI. Acidification -   TP. Tanning process -   BAS. Basification -   CF. Collagen fiber -   Y. Yarn -   YSP. Yarn spinning -   FMP. Fabric manufacturing process -   F. Fabric -   D. Dyeing -   SF. Staple fiber -   S. Shoe -   UP. Upper part -   SO. Sole -   SL. Shoe lining -   PD. Pre-dyeing -   SP. Spool -   RE. Red -   BL. Blue -   YE. Yellow 

1. A method of dyeing collagen fiber, the method comprising steps of: providing collagen fiber; and dyeing the collagen fiber. 2.-3. (canceled)
 4. The method according to claim 1, wherein the collagen fibers are reconstructed fiber staple fibers produced based on a number of mechanically sub-divided or grinded protein fibrils. 5.-12. (canceled)
 13. The method according to claim 1, wherein the collagen staple fiber is spun into a yarn, and wherein a color of the yarn is subsequently modified into a neutral base color.
 14. The method according to claim 13, wherein the yarn is modified into the neutral base color and then reeled into a plurality of reels having the neutral base color.
 15. (canceled)
 16. The method according to claim 13, wherein the yarn having the neutral base color is reeled into a plurality of yarn reels.
 17. The method according to claim 13, wherein the yarn in a neutral base color is rolled up on a plurality of reels prior to dyeing, and wherein, subsequently, a subset from the plurality of spools is selected for dyeing the yarn in one color and another subset from the plurality of spools is selected for dyeing the yarn in another color. 18.-22. (canceled)
 23. A method of manufacturing a collagen yarn, the method comprising: spinning a collagen-based staple fiber into a yarn by spinning of a plurality of collagen staple fibers into a yarn, wherein the yarn comprises a spun bundle of collagen staple fibers, and wherein the manufactured yarn is subsequently subject to dyeing.
 24. The method according to claim 23, wherein the dyeing of the collagen yarn is performed subsequently to the spinning of staple fibers into a yarn and prior to a further step of processing the yarn into a fabric. 25.-31. (canceled)
 32. The method according to claim 23, wherein a percentage by weight of collagen in the collagen yarn is at least
 20. 33. The method according to claim 23, wherein a percentage by weight of collagen in the collagen yarn is at least
 70. 34.-35. (canceled)
 36. The method of claim 23 further comprising: dyeing a collagen fabric comprising collagen fiber, wherein the collagen fabric is provided on the basis of the collagen yarn, wherein the yarn is spun on based on a plurality of collagen staple fibers, and wherein the fabric is subject to the dyeing. 37.-42. (canceled)
 43. The method according to claim 36, wherein a percentage of collagen in the fabric is at least 70 percent by weight of the collagen. 44.-53. (canceled)
 54. The method according to claim 23, wherein the collagen yarn comprises non-collagen protein.
 55. The method according to claim 23, wherein the collagen yarn comprises 1 to 60% by weight of non-collagen protein. 56.-59. (canceled)
 60. A leather yarn formed via a method the method comprising: spinning a collagen-based staple fiber into a yarn by spinning of a plurality of collagen staple fibers into a yarn, wherein the yarn comprises a spun bundle of collagen staple fibers, and wherein the manufactured yarn is subsequently subject to dyeing, wherein a color of the yarn is provided in a neutral base color.
 61. The leather yarn according to claim 60, wherein the yarn in the neutral base color is reeled up on a plurality of reels.
 62. The leather yarn according to 61, wherein the yarn having the neutral base color is rolled up on a plurality of reels prior to the dyeing.
 63. The leather yarn according to 62, wherein the yarn in a neutral base color is rolled up on a plurality of reels prior to dyeing and subsequently a subset from the plurality of spools is selected for dyeing the yarn in one color and another subset from the plurality of spools is selected for dyeing the yarn in another color.
 64. The leather yarn according to 63, wherein the collagen staple fibers have a tenacity of more than 3 g/denier. 65.-68. (canceled)
 69. A leather shoe comprising; a sole; and an upper part, wherein the upper part is at least partly comprised of leather fabric, and wherein the leather fabric is produced based on leather yarn, wherein the leather fabric of the shoe comprises: tanning agents in at least 1% by weight of the leather fabric, and dye in at least 1% by weight of the leather fabric. 70.-80. (canceled) 